I've never purchased a computer book, although I should...Do they actually help you learn better? I've always just used the internet and forums.
Oh, and I forgot to mention. Experts tend to drop little shortcuts all over the place in books you wouldn't otherwise notice. For example, in PHP to run a shell command you normally see something like this:
ob_start();
passthru('echo "hello world"');
$result = ob_get_contents();
ob_end_clean();
OR
$blah = '';
exec('echo "hello world"', $blah);
$result = implode("\n", $blah);
BUT you could simply do this.
$result = `echo "hello world"`
Or if you want to take something like MySQL. Typically group by would be something like this:
SELECT blah, count(*) AS cnt FROM sometable GROUP BY blah, ORDER BY cnt DESC
BUT you can back reference by number, so instead you could do
SELECT blah, count(*) AS cnt FROM sometable GROUP BY 1, ORDER BY 2 DESC
Or you might want to do something like this where you are forced to use count(*) in it's full since there WHERE won't know the alias.
SELECT blah, count(*) AS cnt FROM sometable WHERE count(*) > 10 GROUP BY 1, ORDER BY 2 DESC
Instead, it might be more efficient to do this:
SELECT blah, count(*) AS cnt FROM sometable GROUP BY 1, ORDER BY 2 DESC HAVING cnt > 10
Chances are you aren't going to learn little things like that in your casual browsing.